Track apparatus with laser beam reference

ABSTRACT

A laser beam reference or datum in a track surfacer, liner or surveying apparatus is intercepted by a mask or sensor which is held in a measurably fixed relationship to the grade rail. This sensor is connected with the track lining or leveling tool, or a track position recorder or signaling instrument, and control signals from the sensor in response to laser beam impingement thereon operate the respective tool or recording or signaling instrument.

United States Patent 1 Plasser et a1.

TRACK APPARATUS WITH LASER BEAM REFERENCE Inventors: Franz Plasser;Josef Theurer, both of Johannesgasse, 1010 Vienna, Austria Filed: Aug.30, 1971 Appl. No.: 176,129

Related U.S. Application Data Division of Ser. No. 3,762, Jan. 19, 1970,Pat. No. 3,706,284.

Foreign Application Priority Data Jan. 22, 1969 Austria 646/69 U.S. C1313/287, 104/7 R, 104/8 Int. Cl E0lb 35/08, EOlb 35/10 Field of Search33/287, 1 H; 104/7,

[111 3,750,299 Aug. 7, 1973 [5 6] References Cited UNITED STATES PATENTS3,381,626 5/1968 Fafan et al 33/287 3,591,926 7/1971 Trice, Jr. 33/1 HPrimary ExaminerDrayton E. Hoffman Assistant ExaminerRichard A. BertschAtt0rneyKurt Kelman [57] ABSTRACT A laser beam reference or datum in atrack surfacer, liner or surveying apparatus is intercepted by a mask orsensor which is held in a measurably fixed relationship to the graderail. This sensor is connected with the track lining or leveling tool,or a track position recorder or signaling instrument, and controlsignals from the sensor in response to laser beam impingement thereonoperate the respective tool or recording or signaling instrument.

14 Claims, 19 Drawing Figures PAIENIED ml; 7

SHEET 1 OF 4 PATENTEU M18 7 I975 SHEET 2 0F 4 PATENTEU RUB 7 I975 SHEETt 0F 4 INVENTOR$ Fan 2 Msm BY Josef THEWEQ TRACK APPARATUS WITH LASERBEAM REFERENCE This is a division of copending application Ser. No.3,762, filed Jan. 19, 1970, now US. Pat. No. 3,706,284 dated Dec. 19,I972.

The present invention relates to track surveying apparatus for recordingor signaling the position of a track in relation to a laser beamreference or datum.

In such apparatus, there is provided a laser beam emitter, if desired alaser beam receiver associated with the emitter so as to define the pathof the laser beam, and a laser beam sensing means, such as a mask orsensor, in the path of the laser beam. Means is provided for surveyingthe track position and a recording or signaling instrument forindicating the track position is provided.

A laser beam reference is very useful in track working operationsbecause of its long reach as well as its total insensitivity to weatherconditions, the sharpness of such a beam, and for other reasons. It isaccordingly a primary object of this invention to provide a practicallyuseful laser beam reference for track surveying to make such anapparatus useful for a variety of track surveying operations, toconstruct it with a minimum of sturdy and easily operable parts, andthus to reduce service of the apparatus to a minimum while making itsoperation simple but exceedingly precise.

It is another object of the invention to provide such a laser beamreference for controlling the correction reference system as well as forsimply recording or signaling the misalignment of the track.

The above and othe objects are accomplished according to an essentialcharacteristic of the present invention by providing a laser beamsensing means in the path of the laser beam, which sensing means isconnected with the track position indicating means, for instance a trackposition recorder or a movable anchor for one end of a reference linebelonging to a reference system in relation to which the track movingmeans corrects the track position. Means is provided according to thisessential characteristic of the invention for holding the laser beamsensing means in a measurably fixed relationship, preferably inimmediate contact, with the selected grade rail of the track. Laser beamsensitive elements on the laser beam sensing means produce controlsignals upon impingement of the laser beam on these elements foractuating the control means operating the track position indicatingmeans, i.e. the movement of the reference line anchor, thus assuringproper positioning of the reference line.

The precision of track surveying required in modern track workingapparatus is assured according to the invention by holding the laserbeam sensor in a fixed relationship to the grade rail so that anaccurate reference or datum is formed thereby, and the laser beamresponsive elements on the sensor automatically and continuously surveythe track. Thus, it has been shown to be insufficient merely to providea laser beam reference and sensing means therefor to obtain apractically useful system. Rather, it has been necessary to solve theproblem of accurately positioning the laser beam, i.e.

' its emitter and receiver, as well as the sensor in the path of thebeam, in respect of the track to be corrected, and to coordinate allthese parts of the system in a manner that assures their preferablyautomatic cooperation with the movable parts of the track surveyingmeans without an unduly complex arrangement which would requireexcessive expenditure in service and undue skill in operation. Thepresent invention has solved this problem, making use also of theproperty of laser beams of being much sharper and more well defined thanconventional light beams, for instance, so as to form an exact referenceor datum but also of their intensity and readily controllable change ofintensity to make laser beam sensitive elements most responsive theretounder all conditions.

If the apparatus is used for lining, the laser beam sensor is laterallypressed against the grade rail. In leveling operations, the laser beamsensor will be held in fixed vertical relation to the grade rail by itsown weight.

The apparatus of this invention works with a true laser beam of welldefined cross section which may be rectangular and extend in a singleplane, or may extend in two perpendicularly intersecting planes forminga cruciform or L-shaped cross section. As is known, a laser beammaintains its high definition and intensity for considerable distancesso that a number of sensors may be placed in its path to control varioustrack correction recordings. The sensors may then be so placed in thepath of the laser beam that they mask only a portion of the beam,permitting one sensor, for instance, to control track leveling, anothersensor to control track lining, and so on, while a final portion may bereceived at the receiver to control the position of the laser beam whichis then automatically determined by the positions of the laser beamemitter and receiver.

In accordance with one feature of the invention, the sensors andpreferably the receiver of the laser beam have laser beam sensitivecells or elements so arranged about a center region that any deviationof the beam from its centered position will immediately produce controlsignals which will move the sensor and/or receiver back into itscentered position. Thus, the sensor 'may be an apertured stop or maskwith a central aperture having the same cross section as that of thelaser beam, which aperture is surrounded by light-and/or temperaturesensitive elements which produce control signals for moving the sensorback into its centered position upon impingement of the laser beam onsuch elements. The receiver may have a similarly arranged pattern oflaser beam sensitive elements about a nonsensitive central region. Thus,the entire laser beam reference or datum will remain constantly andautomatically focussed while simultaneously being in a fixedrelationship to the grade rail.

It is also possible within the principles of the present invention touse fixed points or markers along the track as targets for the laserbeam, which points have a given distance from the grade rail, and tosurvey the track position in respect of such fixed points with the laserbeam as a reference. In such apparatus, the laser beam emitter is on anadjustable support movable along the track, which support may beadjusted by remote control in respect of the selected grade rail of thetrack.

The above and other objects, advantages and features of the presentinvention will become more apparent in the following detaileddescription of certain now preferred embodiments thereof, taken inconjunction with the accompanying drawing wherein FIG. 1 is a schematicside view of a combined track tamper-surfacer-liner with an embodimentof the reference system of this invention;

FIG. 2 is a top view of the embodiment of FIG. 1;

FIG. 3 is a schematic perspective view of essential parts of thereference system;

FIGS. 4a and 4b show a modified detail of the reference system in sideand front view, respectively;

FIG. 5 is a schematic top view of a track liner with an embodiment ofthe reference system of the invention;

FIG. 6 is a section along line VI-Vl of FIG. 5;

FIG. 7 is a section along line VII-VII of FIG. 5;

FIG. 8 is a section along line VIII-VIII of FIG. 5;

FIG. 9 is a schematic top view of a modification of the system of FIGS.5 to 8;

FIGS. 10 to 12 illustrate various embodiments of laser beam receivers;

FIG. 13 is a perspective view of a planar laser beam and its emitter;

FIGS. 14 to 16 are schematic top views of various track correctionmachines embodying the invention; and

FIGS. 17 and 18 are perspective views of additional machines embodyingthe invention.

Referring now to the drawing, wherein like reference numerals designatelike parts functioning in a like manner, FIGS. 1 and 2 show a generallyconventional combined track tamper-surfacer-liner which has a machineframe I mounted on three running gears 2 for mobility on track rails 3.The illustrated track working assembly carries a pair of tamping units 4arranged to tamp two immediately adjacent ties 5 simultaneously, in themanner more particularly disclosed and claimed in our US Pat. Nos.3,372,651 and 3,357,366. The machine frame 1 also carries roller liningunits 6 each of which includes two flanged rollers 7 glidingly grippingthe heads of rails 3. Lining cylinders 9 are connected to the liningunits for transmitting laterally directed power to a respective rail forpressing the track into the correct lateral position, as isconventional. The track lining actuating means 6, 7, 9 is verticallyadjustable on the front end of the machine frame 1, as seen in theworking direction of the machine indicated by a horizontal arrow, bymeans of a pressure fluid drive 8.

The reference system for lifting the track to a desired level or gradeincludes a reference consisting of a conical light beam 12 emitted fromsender 11 mounted on bogie 10, which is positioned in an uncorrectedtrack section, and received by receiver 13 mounted on machine frame 1for free vertical movement in respect thereto and resting directly ontrack 3 in a track section that has been corrected, the receiver 13 thusbeing vertically movable with this track section when the same iscorrected. A light beam interceptor or mask 14 is also mounted for freevertical movement on track 3 in a track section intermediate the senderand receiver. As is conventional in this type of track grading referencesystem, actuation of the lifting cylinder 8 is terminated and thecorrect track level is indicated when the mask 14 has moved upwardlywith track 3 to the point where it intercepts the lower portion of theconical light bundle 12 to leave a lower straight line of light parallelto the desired level of the track and the light receiver below this lineis prevented from receiving light.

The bogie 10, which may also carry track measuring and recordingdevices, such as cross levels, is connected to the front of the machineframe 1 by means of spacing rod 15, which keeps the bogie at apredetermined distance from the frame as the track working apparatusproceeds along the track during the surfacing and/or lining operation,the corrected track section always lying behind the units 6 while thebogie 10 runs on the uncorrected track section.

To avoid local falsification of the track correction due to an unusuallow or high point in the uncorrected track section, the verticalposition of light emitter 11 is constantly observed by means of a scale11" on bogie 10. For this purpose, a source or emitter 17 of a planarlaser beam 16 is mounted on front bogie 19. The laser beam is conical ina transverse plane substantially parallel to the plane of the track. Thelaser beam source 17 is mounted on a vertically adjustable carriersupport 18 on bogie 19 which may be pivoted about a vertical axis sothat the laser beam source 17 may be selectively positioned intoassociation with a selected rail of the track, as best seen in FIG. 2.Such adjustment is necessary when the grade rail is changed, i.e. whenadjacent track sections form curves extending in opposite directions. Ascale is associated with the laser beam source to facilitate suchadjustment in track curves. The laser beam source 17 is additionlllypivotal about a horizontal axis extending transversely of the track.

The front bogie 19 has its own drive, which is preferably actuated byremote control, and runs on two running gears 19. The running gears haveflanged wheels or rollers which are pressed against the selected graderail so as to constitute a proper reference in respect of the track andto bring the laser beam source 17 into proper relationship to thereference system. Lateral pressure may be exerted in any convenientmanner, such as by jacking means, as is well known.

The bogie 10 also runs on two running gears 10' which have flangedwheels or rollers which are pressed against the selected grade rail inany convenient manner. A laser beam mask or interceptor 20 is mounted onbogie 10 for 180 pivotal movement about a vertical axis so that is maybe swung around to a selected grade rail in the same manner as the laserbeam source 17.

The machine frame 1 carries a laser beam receiver 21 which is alsomounted for 180 pivotal movement about a vertical axis so that it, too,may be swung around to the selected grade rail, with laser beam source17 and laser beam sensing mask 20. The laser beam receiver 21 is mountedin substantial alignment with the light beam receiver 13.

A second laser beam sensor or mask 22 is similarly pivotally mounted onmachine frame 1 in substantial alignment with the tamping units 4 forfurther control of the desired track correction. As best seen in FIG. 2,this mask also is in the path of a portion of the outwardly taperingplanar laser beam 16.

The laser beam emitter 17 is first coarsely centered on receiver 21 byviewing a spotboard 24 (FIG. 3) through sight 23, the spotboard beingspaced the same distance from the center of the receiver as the sight isfrom the center of the emitter. Accurate centering of the planar laserbeam 16 during the continuous operation of the track correctionapparatus is effected automatically by remote control, either by radio25 (FIG. 1) or by an electrical control circuit 26 (FIGS. 2 and 3). Forthis purpose, the receiver 21 has a grating or scanning pattern oflightand/or temperature sensitive cells which respond to the laser beamintensity received thereby to produce corresponding electrical controlor radio signals for actuating pivoting drive 17 for the emitter 17and/or pivoting drive 21 for the receiver.

As seen in FIG. 3, the laser beam sensor masks 20 and 22 also carrylightand/or temperature sensitive cells or elements 27 and 28. Theseradiation responsive elements 27 and 28 extend horizontally above andbelow a horizontally extending, fixed central region of the masks, i.e.an open slot, the elements 27 and 28 responding to the laser beamintensity received thereby to produce corresponding electrical controlsignals characteristic of each element for energizing electrical controlcircuit 29 to actuate the vertical movement of a respective sensor independence on the impingement of planar laser beam 16'.

' The vertical movement of the sensor 20 actuates vertical drive 11 forlight beam emitter 1 1 so that the vertical position of the same iscorrected if it is in the wrong vertical position when the bogie isstationed at an unusually low or high point in the uncorrected tracksection during the continuous advance of the apparatus along the trackon which work is done. The vertical adjustment of the sensor 22 mayberecorded on a moving band 30. Also, a conventional pendulum device 31may be mounted in the region of mask 22 to observe and control thesuperelevation of the track in relation to the plane of laser beam 16.According to an important characteristic of the present invention, allparts of the reference system are pressed into contact with the graderail to assure accuracy.

As appears clearly from FIGS. 2 and 3, each of the laser beamintercepting means and 22, which are spaced apart along the longitudinalextension of the beam, are arranged to interfere with, or intercept,only a portion of the lateral extension of the planar laser beam so thatpreferably at least the central portion of the beam is left unmasked andmay be received by receiver 21.

In the modification shown in FIGS. 4a and 4b, the laser beam maskingmeans is constituted by a slotted stop 32. While the stop has been shownto define a horizontal slot 33 surrounded by a lightand/or temperaturesensitive cell or element 34, this slot may instead extend vertically orbe replaced by a circularly shaped aperture. Also, only one side of thestop adjacent the slot or aperture need be lightand/or temperaturesensitive, instead of all sides. The illustrated stop is useful inassociation with the horizontal laser beam 16, as shown in FIG. 13, anda difierently shaped and/or positioned aperture would be used with alaser beam of different shape and/0r position. As in the previouslydescribed modification, the mask 32 is vertically movable by drive 11'.

The mobile track liner illustrated in FIGS. 5 to 8 operates in themanner fully described in Austrian Pat. No. 227,749 and, sinceconventional, will be described herein only inasmuch as pertinent to thereference system of the present invention. This track working apparatuscomprises a series of carriage spaced apart in the direction of trackelongation for movement on the track rails on one or two axles. As seenin the working direction, the apparatus comprises a rearmost carriage35, preceded by a measuring bogie 36, track lining unit 37 and frontcarriage 38. Preferably, all of these carriages are independentlymounted for lateral movement on the underside of the mobile machineframe 39 which has its own running gears (not shown) for mobility on thetrack. The operators cab 40 is mounted on the frame 39.

The axles of the carriages have flanged wheels and conventional means isprovided for laterally pressing the carriages against the selected graderail of the track until the flanges of the wheels engage firmly againstthe selected rail. The lateral pressure means may include a laterallymovable second axle (shown in broken lines) or a pair of double-actingjacks 41.

in the reference system used for track alignment according to theabove-mentioned patent, a long reference chord 42 extends from rearmostcarriage 35 to front carriage 38, passing intermediately positionedmeasuring bogie 36. The anchor points of the long chord are laterallymovable on their respective carriages by a spindle drive 43 rotated byservo motor 43'. The short reference chord 44 has one end point anchoredto the rear carriage 35 at the same anchorage as long chord 42 while theother end point of the short chord is anchored to the track lining unit37 to be laterally moved therewith with track 3 and the roller unit 37when the latter is actuated, the short reference chord also passingintermediately positioned measuring bogie 36. This two-chord liningsystem is well known and requires the ordinates on the two chordsmeasured at 36 to be in the same proportion in a track curve as theproportion of lengths of the two chords. The track 3 is laterally movedby roller lining units 37 until the ordinates at 36 have reached thisproportion, two chord probes being mounted on screw-threaded spindle 36for automatically determining the alignment in the manner fullydescribed and claimed in our U. S. Pat. No. 3,314,373.

To avoid local falsification of the track lining due to a sharplyout-of-line position of front carriage 38 in the uncorrected tracksection, the known reference system is associated with a laser beam 45extending laterally adjacent track 3 in the direction of elongation ofthe track. The position of the laser beam may be fixed by end points 46and 47 which may be arranged at regular intervals along the track at apredetermined distance from the theoretical center line of the track.

A foremost carriage 48 precedes the track lining apparatus in theworking direction to support the laser beam receiver 50. For thispurpose, a spindle drive 43 operated by servo motor 43' is mounted onthe carriage, the spindle drive having a support arm 49 projectinglaterally beyond the track and supporting the receiver 50 at apredetermined point which may be adjusted by rotation of the spindledrive, regardless of the actual lateral position of the track section.The laser beam receiver 50 is pivotally mounted on the support arm 49.The laser beam source or emitter 51 is similarly pivotally mounted onthe support arm 49 projecting laterally beyond the track from spindledrive 43 on rear carriage 38 and whose lateral position is adjustablesimilar to that of receiver 50. As in the previously describedembodiment, the laser beam emitter carries a sight 23 for viewing aspotboard on the receiver so as to focus the emitter on the receiver. Atelevision receiver and screen 53in the operators cab is connected tothe laser beam emitter to enable the operator to focus the emitter byremote control circuit 53' actuating the pivotal movement of theemitter.

Accurate centering of the laser beam 45 during the continuous operationof the track liner is effected automatically by remote control circuits52 and/or 53, the control circuits being actuated by signals from thescanning pattern of lightand/or temperature sensitive cells on reciever50 (see FIG. 6). Automatic focusing is effected by vertically movingand/or pivoting sender 51 and/or receiver 50. As shown in FIG. 7, thelaser beam 45 is of rectangular cross section and defines a verticalreference plane extending in the direction of track elongation. Thiscross sectional shape of beam 45 facilitates the control of the emitter51 in dependence on the receiver as well as the masking or interceptionof the beam by sensing means 54 also mounted for lat- -eral movement onsupport arm 49 of spindle drive 43 which is arranged on the carriage 38.The lateral movement of the mask 54 is controlled automatically bycontrol circuit 55' connected to servo motor 43' of its spindle drive,the control circuit being acutated by signals from lightand/ortemperature sensitive elements 55 mounted laterally adjacent the beam45, as seen in FIG. 7. Thus, the masking or sensing means 54 constitutesa probe for the laser beam and, depending on which of the lateralcontact elements 55 is intersected by the laser beam, a correspondingcontrol signal will rotate the spindle drive 43 in one or the otherdirection to move the probe back into alignment with the beam 45.

When the probe 54 is in perfect alignment with the laser beam 45, i.e.when its elements 55 are out of contact with the beam, the forward endof the longer chord 42 has exactly the same distance from laser beam 45as its rear end on carriage 35. In a track curve, the lateral adjustmentof the arm 49 on carriage 38 takes into account the correspondingordinate, for which purpose the arm carries scale 49".

The arms 49 on carriages 35, 38 and 48 may be pivoted 180 about avertical axis so that they may be associated with the other rail of thetrack when a change of grade rail is required. The carriages themselvesare relatively light and readily exchangeable so that the apparatus maybe used in reverse working direction.

It is not essential for the laser beam emitter and receiver to bemounted on laterally adjustable support arms. They may be moved or fixedat a fixed lateral distance x from fixed points 46 and 47 which have apredetermined lateral distance from the grade rail or center line of thetrack. For instance, as indicated in FIG. 6, the receiver may be clampedto a stake 46 at 49' (the emitter being similarly mounted). Or, as shownin FIG. 8, the emitter 51 may be mounted on a third rail 56 (thereceiver being similarly mounted). As indicated in broken lines in FIG.5, the outer ends of respective support arms 49 may contact the fixedpoints 46 and 47.

FIG. 9 schematically illustrates a different reference system forlining, this system, too, being associated with a laser beam 45. In thissystem a single reference line 57 is provided whose front end is movedinto a predetermined position in relation to the laser beam 45 so thatthe line 57 fonns a proper reference for movement of the lining unit 37which, in this embodiment, is preferably arranged closer to the rearcarriage 35 than the front carriage 38.

The installation of the laser beam reference plane will be facilitatedby the use of optical and/or acoustical control signals indicating theproper spacing from the fixed points 46 and 47.

The embodiment of the laser beam receiver 21 shown in FIG. 10 isdesigned for a laser beam 16a consisting of two perpendicularlyintersecting planar beam portions. The lightand/or temperature sensitivecells or elements 58 of the receiver are distributed in quadrantssurrounding an imaginary cross centered on the receiver andcorresponding to the cross section of the laser beam. Thus, when thebeam deviates from its centered position, it will promptly impinge onone or more elements 58 producing a signal to indicate such deviation.

In the embodiment of the laser beam receiver shown in FIG. 11, a crosssectionally L-shaped laser beam 16' is to be sensed, the two legs of theL having positioned adjacent thereto light sensitive elements 58 andtemperature sensitive elements 58'. Any movement of the laser beam offcenter, as indicated by the horizontal and vertical arrows, will producea corresponding signal as soon as one or both legs of the beam impingeupon one or more of the elements 58 and/or 58.

FIG. 12 shows an embodiment of a laser beam receiver 21 designed tosense two parallel, spaced-apart laser beams 16", 16". In this receiver,two centrally positioned lightand/or temperature sensitive elements 58",58" are provided on the receiver intermediate the two laser beams. Asthe two coordinated laser beams move off center in a vertical direction,one or the other beam will impinge on a respectively adjacent element58" to produce a corresponding signal.

FIG. 13 shows a horizontally extending, planar laser beam 16 whichconstitutes a true datum or reference for leveling or grading the trackin respect thereto.

FIG. 14 shows a track liner with a mobile machine frame 60 havingrunning gears 61 moving on track 3 to be lined by means of roller liningunit 62 whose flanged wheels engage the rails. A bogie 63 runs on thetrack in the region of the track lining means 62 and serves as theforward anchor of the shorter reference chord 64, similarly to theembodiment of FIG. 5. As in the other embodiments and forming part ofthe lining reference system, the bogie 63 may be pressed into engagementwith the selected grade rail to assure the accuracy of the referencepoint. The shorter chord 64 extends rearwardly to rear carriage 66 whichalso anchors the rear end point of the second, longer reference chord 65whose forward end point is anchored to front carriage 67.

Forming part of the lining reference system, the carriages 66 and 67also have flanged wheels with which they may engage the selected graderail under lateral pressure so that each point of the reference systemproduces an accurate reference defined by the grade rail. As previouslypointed out, the lateral pressure may be exerted by preferablyhydraulically operating jacks which may either be double-acting orconstitute a second carriage axle, pressure means of this type and forthis purpose being known per se.

The measuring bogie 68 intermediate the rear carriage 66 and the liningunit 62 senses the actual ordinate of the longer chord 65, which isconverted into the desired ordinate for shorter chord 64, the ordinateof the shorter chord being in a proportion to that of the longer chorddetermined by the proportion of the lengths of the two chords, all ofwhich is well known. The track 3 is laterally moved by unit 62 until thedesired ordinate of shorter chord 64 at measuring bogie 68 has beenreached. The hydraulic motor 62' of unit 62 is automatically controlledby electric control circuit 68' which is actuated by a control signalfrom control device 68" associated with chord 64 on bogie 68. Thecontrol device may be mechanially operated by the short chord 64 or itmay be a rotary potentiometer operated by the chord to produce thedesired control signals. I

This known lining reference system is positioned in relation to a laserbeam 70 extending laterally of the track in the direction of trackelongation. For this purpose, the rear station 66 of the liningreference system carries a pivotally mounted support arm for the laserbeam source or emitter 69 so that the emitter may be swung into positionalongside either rail of the track. A foremost carriage 73 carries asimilarly pivotally mounted support arm projecting laterally beyond theselected rail to support the apertured stop 71 in the path of the laserbeam. Like carriage 66, the carriage 73 also has flanged wheels whichmay be laterally pressed into contact with the selected rail. The stop71 has lightand/or temperature sensitive elements (cells) on both sidesof the aperture or slot of the stop to produce control signals whichautomatically actuate the control drive or servo motor 71 forpositioning the stop 71 so that the laser beam is centered or focused onits aperture, the laser beam emitter 69 being simultaneously centered bythe control signals via conrol circuit 72'.

A laser beam reflector 74 is mounted on the stop 71 behind its apertureto deflect the laser beam passing through the aperture when it isproperly focused by the above-described automatic control or centeringmeans. Carriage 73 mounts a second reflector 74' roughly in verticalalignment with the center line of the track, the two reflectors beingarranged to deflect the laser beam each time by 90, i.e. to return itfrom reflector 74' in the same direction whence it arrived, i.e. backtowards the previously lined track section.

Front carriage 67 of the linging reference system carries a laser beamreceiver or target 75 whereon the laser beam coming from reflector 74impinges. The target 75 is fixedly connected to the anchor 75a of theforward end of longer reference chord 65 and is laterally movabletherewith on carriage 67. This target 75, too, has lightand/ortemperature sensitive elements whose control signals automaticallycenter the target in respect of the laser beam so that the forward endof the longer reference chord 65 is automatically moved into a desiredlateral position at which it is at exactly the same lateral distancefrom laser beam 70 as the rear end of the chord 65 is from the beam inthe lined track section. As is known, the ordinate of the curve must betaken into consideration when the apparatus works in a track curve.

If desired, the laser beam reflectors 74 and 74' may be replaced by atarget at 74 and an independent laser beam emitter at 74' which has afixed distance to the target at 74. This modification is functionallyequivalent to the one above-described since, in fact, the reflector 74can be considered a laser beam target and the reflector 74 a'laser beamemitter.

' In the track liner of FIG. 15, a very simple lining reference systemis used, like reference numerals in this figure designating parts thatfunction in the same manner as in the embodiment of FIG. 14. Thedatum'line for the reference system is again provided by laser beam-70generated by emitter 69 and passing through apertured stop 71 to target74. As in previously described embodiments, the emitter 69 may carry asight 23 for coarse focusing on target 74. The laser beam emitter andtarget are mounted on fixed points 46 and 47 adjacent the track so thatthe laser beam datum line requires no further auxiliary devices todetermine its position. A signal, such as warning light 74", may beprovided at the laser beam target 74 to enable an operator to adjust theposition of the laser beam emitter 69 as to focus or center the beam onthe target or a spotboard connected thereto.

The laser beam sensing means is an apertured stop 71 mounted in the pathof the beam and is laterally pressed by jack 41 against the grade railof the track 3 so as to indicate the actual position of the track to belined. The stop carries lightand/or temperature sensitive elements 72laterally adjacent the aperture of the stop (and the laser beam) so asto produce control signals when the beam deviates from the centeredposition, which signals actuate control circuit 72' operating control orservo motor 77 for the double-acting jack 62' of the lining unit 62. Theelectric motor 77 operates a hydraulic supply and valve system 77' forcontrolling the operation of jack 62'. The track 3 is laterally moved bythe unit 62 until the laser beam passes through the aperture of stop 71,at which time the elements 72 emit no control signals. The stop may belaterally moved so as to compensate for the ordinate in track curves,i.e. the greater distance of the curved track from the straight datumline or plane.

FIG. 16 illustrates a very useful embodiment of a track workingapparatus wherein a single laser beam datum cooperates with a series ofsensing means spaced along the track elongation in the path of the beamso that the same beam may be used for a variety of pur poses along thetrack, i.e. for leveling, lining, recording or merely indicating thetrack position. For this purpose, it is particularly advantageous if thelaser beam 16 is of cruciform or L-shaped cross section, such as shownin FIGS. 10 and 11, so that the spaced laser beam sensing means mayintercept different cross sectional portions of the beam. Such sensingmeans may be arranged, if desired, on a series of different trackworking machines advancing along the track in the same working directionbut being otherwise independent of each other, particularly since thereach of a laser beam may extend to more than 600 feet.

The track working apparatus schematically shown in the top view of FIG.16 includes a combined tamper-leveler-liner similar to the oneillustrated in FIGS. 1 and 2 but comprising two lining units 6 and 62.Since the same reference numerals are used to desighate like partsfunctioning in a like manner, redundancy will be avoided in thedescription of this figure by referring to the preceding description ofFIGS. 1 to 3, the laser beam being of cruciform cross section.

Seen in the working direction, the laser beam is first intercepted bysensor 20 which may have the form shown in FIG. 3 and intercepts thathorizontal leg of the beam which extends inwardly toward the track. Whenimpinging upon the lightand/or temperature sensitive elements of thesensor 20, this leg of the laser beam will produce control signalsacutating control circuit 29 to adjust the vertical position of lightemitter 11. This wlll cause the light beam 12, which is used as areference line for leveling the track, to assume a position parallel tothe desired level of the track 3.

The next sensor 20a is spaced rearwardly of sensor ,20 and is arrangedto intercept the upwardly extending leg of the cruciform laser beam 16.It is associated with the roller lining unit 6 which laterally moves thetrack to produce at least coarse lining. The jack 9 of the lining unitis operated by the servo motor 76 which is actuated by control circuit75' receiving the control signals from the sensor 20a.

The third and rearmost sensor 20b is associated with the roller liningunit 62 and is arranged to intercept the downwardly extending leg of thecruciform laser beam. The control signals from the sensor are fed tocontrol circuit 76 operating relay 78 for controlling the lateralmovement of the unit 62 which may be used for fine lining the track.

The portion of the laser beam 16 which has not been intercepted bysensors 20, 20a and 20b, particularly its center and remaining parts ofits legs, are received by receiver 21 and used to center or focus thesame in re spect of emitter 17. This receiver is mounted on a laterallyprojecting support arm 79 on rearmost carriage 80 on which the supportarm is mounted for lateral movement in respect of the track so that thereceiver 21 has the same distance from the center line or grade rail ofthe track as the emitter 17 whereby the laser beam 16 assumes a positionparallel to the center line of the track in a vertical and horizontaldirection. All parts of the reference system requiring an accuraterelationship with the actual position of track 3 are provided withbiasing or pressure means 41 enabling such parts to be pressed intocontact with the grade rail.

FIGS. 17 and 18, finally, illustrate track work carried out according tothe principles of the present invention, using solely a fixed point 46along the track as datum for the work.

As shown, a front carriage 38a runs on track 3 and carries a supportframe 81 for the laser beam emitter 82. The emitter 82 is mounted at theoutward end of a support arm 84 being laterally movable by a spindledrive operated by servo motor 84 which may be remote controlled. Thecarrier 81 of the support arm may be pivoted about a vertical axis sothat the emitter 82 may be swung into association with either one of thetrack rails. As in all embodiments, the carriage 38a, which forms partof the reference system, is pressed into contact with the selected graderail to form an accurate reference basis according to the actualposition of the track. The planar laser beam 83, which flares outwardly,is focussed vertically downwardly against the fixed receiver 46.

The track lining in reference to the laser beam 83 is effected by thetwo-chord system more fully described hereinabove and known per se,which includes the chords 42 and 44 cooperating in the manner describedin connection with FIG. 5, like reference numerals designating likeparts functioning in a like manner to avoid redundancy in thedescription. The forward anchor point 42 of the longer chord 42 isfixedly connected with the laterally movable support arm 84 and thus ismoved therewith into the desired position of the track, regardless ofthe actual position of the track at this point, as long as the lateralposition of the sender is adjusted into vertical alignment with thefixed track point 46. This imparts the desired alignment to the entirechord 42 since its rear anchor is on carriage 35a in the previouslylined track section.

As soon as the chord 42 has assumed the correct position or alignment,the track may be laterally moved by track lining unit 37a until theforward end of the shorter reference chord 44, which is anchored to thebogie 37' at the lining unit 37a and moves laterally therewith, hasmoved the chord so that the ordinate ratio at the measuring bogie 36a,which includes the probes 36' for the chords, has the desired value.Operator actuates the control 86 which is connected to servo motor 84'by control circuit 87 to move the support arm 84 transversely of thetrack until he ascertains visually that the planar laser beam 83 is inalignment with the fixed receiver 46.

In the extremely simple track liner of FIG. 18, a roller lining unit 37bhas journaled therein a laterally movable support arm 84 carrying thelaser beam emitter 82. The planar laser beam is again downwardlyfocussed on fixed receiver 46. The track lining unit 37b has the usualdouble flanged wheels gripping the rail heads and a double-acting jack(not shown) for laterally moving the wheels in either lateral directionto line the track, the lateral stroke of the unit being terminated whenthe laser beam 83 is in alignment with the aperture or other marker onreceiver 83, which may be visually determined, the arm 84a and emitter82 moving laterally with the unit during the lining stroke.

We claim:

1. A track surveying apparatus for indicating a desired correction ofthe position of an uncorrected track section in relation to a laser beamdatum, comprising 1. a laser beam emitter positioned in the uncorrectedtrack section;

2. means for controlling the path of the laser beam;

3. means for pressing the laser beam path controlling means into ameasurably fixed relationship to a selected grade rail of the tracksection; and

4. a reference system indicating the desired position of the tracksection,

a. the reference system including an end movable in relation to thetrack section, and

b. the movable reference system end being connected to the laser beampath controlling means for moving the end in dependence on the laserbeam path.

2. The track surveying apparatus of claim 1, wherein the laser beam pathcontrolling means comprises laser beam sensitive elements producingindicating signals upon impingement of the laser beam on said elements.

3. The track surveying apparatus of claim 2, further comprising arecording instrument for recording the indicating signals.

4. The track surveying apparatus of claim 2, wherein the laser beamemitter is arranged to emit a laser beam extending in at least oneplane, and the laser beam sensitive elements are arranged to interceptthe laser beam only partially.

5. The track surveying apparatus of claim 4, wherein the laser beamextends in two perpendicularly intersecting planes.

6. The track surveying apparatus of claim 5, wherein the intersectinglaser beam planes meet along a common axis extending in the direction oftrack elongation.

7. The track surveying apparatus of claim 4, wherein the last beamemitter is arranged to emit two parallel planar laser beams.

8. The track surveying apparatus of claim 2, wherein the laser beamsensitive elements are arranged about a central region of the laser beamboth controlling means, and said signals automatically centering thelaser beam path controlling means in respect of the laser beam.

9. The track surveying apparatus of claim 2, further comprising a servomotor responsive to the signals for adjusting the-emitter.

10. The track surveying apparatus of claim 1, further comprising meansfor pressing the laser beam emitter into a measurably fixed relationshipto a selected grade rail of the track section.

11. The track surveying apparatus of claim 10, further comprising aforward carriage in the uncorrected track section supporting the laserbeam emitter; a laser beam target in the path of the laser beam; a rearcarriage in a previously corrected track section and supporting thelaser beam target; and means for pressing the rear carriage into ameasurably fixed relationship to the selected grade rail.

12. The track surveying apparatus of claim 1, wherein the laser beampath controlling means comprises laser beam sensitive elements producingindicating signals upon impingement of the laser beam on said elements,and a remote control for aligning the laser beam emitter with theelements in response to the signals.

13. A track surveying apparatus for indicating a desired correction ofthe position of an uncorrected track 14- section in relation to a laserbeam datum, comprising 1. a laser beam emitter positioned in theuncorrected track section;

2. a support for supporting the laser beam emitter, a. the support beingadjustable in respect of a selected grade rail of the track section andb. the support being movable along the track section;

3. a laser beam target comprising laser beam sensitive elementsproducing indicating signals upon impingement of the laser beam on saidelements, alignment of the laser beam with selected ones of the elementscontrolling the path of the laser beam, a. the position of the targetbeing fixed in relation to the grade rail; and

4. a reference system indicating the desired position of the tracksection connected to the laser beam emitter support for adjusting thereference system in response to the support adjustment upon alignment ofthe laser beam with the selected elements.

14. The track survey apparatus of claim 13, further comprising a remotecontrol for adjusting the laser beam emitter support.

1. A track surveying apparatus for indicating a desired correction ofthe position of an uncorrected track section in relation to a laser beamdatum, comprising
 1. a laser beam emitter positioned in the uncorrectedtrack section;
 2. means for controlling the path of the laser beam; 3.means for pressing the laser beam path controlling means into ameasurably fixed relationship to a selected grade rail of the tracksection; and
 4. a reference system indicating the desired position ofthe track section, a. the reference system including an end movable inrelation to the track section, and b. the movable reference system endbeing connected to the laser beam path controlling means for moving theend in dependence on the laser beam path.
 2. means for controlling thepath of the laser beam;
 2. a support for supporting the laser beamemitter, a. the support being adjustable in respect of a selected graderail of the track section and b. the support being movable along thetrack section;
 2. The track surveying apparatus of claim 1, wherein thelaser beam path controlling means comprises laser beam sensitiveelements producing indicating signals upon impingement of the laser beamon said elements.
 3. The track surveying apparatus of claim 2, furthercomprising a recording instrument for recording the indicating signals.3. a laser beam target comprising laser beam sensitive elementsproducing indicating signals upon impingement of the laser beam on saidelements, alignment of the laser beam with selected ones of the elementscontrolling the path of the laser beam, a. the position of the targetbeing fixed in relation to the grade rail; and
 3. means for pressing thelaser beam path controlling means into a measurably fixed relationshipto a selected grade rail of the track section; and
 4. a reference systemindicating the desired position of the track section, a. the referencesystem including an end movable in relation to the track section, and b.the movable reference system end being connected to the laser beam pathcontrolling means for moving the end in dependence on the laser beampath.
 4. a reference system indicating the desired position of the tracksection connected to the laser beam emitter support for adjusting thereference system in response to the support adjustment upon alignment ofthe laser beam with the selected elements.
 4. The track surveyingapparatus of claim 2, wherein the laser beam emitter is arranged to emita laser beam extending in at least one plane, and the laser beamsensitive elements are arranged to intercept the laser beam onlypartially.
 5. The track surveying apparatus of claim 4, wherein thelaser beam extends in two perpendicularly intersecting planes.
 6. Thetrack surveying apparatus of claim 5, wherein the intersecting laserbeam planes meet along a common axis extending in the direction of trackelongation.
 7. The track surveying apparatus of claim 4, wherein thelast beam emitter is arranged to emit two parallel planar laser beams.8. The track surveying apparatus of claim 2, wherein the laser beamsensitive elements are arranged about a central region of the laser beamboth controlling means, and said signals automatically centering thelaser beam path controlling means in respect of the laser beam.
 9. Thetrack surveying apparatus of claim 2, further comprising a servo motorresponsive to the signals for adjusting the emitter.
 10. The tracksurveying apparatus of claim 1, further comprising means for pressingthe laser beam emitter into a measurably fixed relationship to aselected grade rail of the track section.
 11. The track surveyingapparatus of claim 10, further comprising a forward carriage in theuncorrected track section supporting the laser beam emitter; a laserbeam target in the path of the laser beam; a rear carriage in apreviously corrected track section and supporting the laser beam target;and means for pressing the rear carriage into a measurably fixedrelationship to the selected grade rail.
 12. The track surveyingapparatus of claim 1, wherein the laser beam path controlling meanscomprises laser beam sensitive elements producing indicating signalsupon impingement of the laser beam on said elements, and a remotecontrol for aligning the laser beam emitter with the elements inresponse to the signals.
 13. A track suRveying apparatus for indicatinga desired correction of the position of an uncorrected track section inrelation to a laser beam datum, comprising
 14. The track surveyapparatus of claim 13, further comprising a remote control for adjustingthe laser beam emitter support.